Field of the Invention
The invention relates to a temperature measurement device, and more particularly, to a temperature measurement device for optical pickup units (OPUs) of optical disc drives.
Description of the Related Art
In optical disc drives, an environment temperature of the optical pickup units influences recording and/or reading operations. For example, for a DVD-RW drive, the characteristics of a Laser Diode (LD) varies with temperature, and thus a temperature surrounding the LD of an optical pickup unit is detected to adjust the write strategy or recording power when writing data to the DVD. Moreover, for a blue-ray disc (BD) drive, the focus offset for recording and reading a BD varies with temperature, and thus an environment temperature of an optical pickup unit is detected to adjust a position of a lens.
FIG. 1 shows a conventional temperature measurement device for an optical disc drive. Referring to FIG. 1, a temperature measurement device 1 comprises an integrated circuit (IC) 10, a resistor 11, a thermistor 12 and a capacitor 13. The resistor 11, the thermistor 12, and the capacitor 13 are external to the IC 10 and on a printed circuit board (PCB). The thermistor 12 is disposed near an optical pickup unit (OPU) of the optical disc drive, and the impedance value of the thermistor 12 varies with variation of the environment temperature of the OPU. Thus, a divided voltage generated at the connection node between the resistor 11 and the thermistor 12 also varies with the variation of the environment temperature of the OPU. The IC 10 can obtain the current value of the environment temperature of the OPU according to the divided voltage. However, the external resistor increases total cost of the optical disc drive.
Thus, a new temperature measurement device is provided at a low cost, particularly for an optical disc drive, which can measure an environment temperature.